1. Technical Field
Embodiments of the invention relate to a control device adapted for use in spinner equipment. More particularity, embodiments of the invention relate to a control device adapted to reduced error (e.g., blockage) in the dispensing of a chemical solution through a nozzle.
This application claims priority under 35 U.S.C. §119 to Korean Patent Application 10-2005-0065141, filed on Jul. 19, 2005, the subject matter of which is hereby incorporated by reference in its entirety.
2. Description of Related Art
The multitude of processes used in the manufacture of a semiconductor device may be generally classified as being related to fabrication, assembly, and test. Fabrication processes, such as impurity diffusion, photoresist formation, material layer etching, and material layer formation, are sequentially performed on the surface of a substrate, such as a wafer, to fabricate an electrical circuit. Fabrication processes are usually complete when the electrical circuit (usually contained in a section of wafer called a die) is fully operable in its “on-wafer” state.
Photolithography processes are a common type of fabrication process. In a typical photolithography process an oxide layer is formed to protect the surface of polished silicon wafer. A photo-etching process is then performed in which a liquid chemical solution is “spun-on” the wafer by dropped the solution onto the oxide layer and then rotating the wafer at high speed to uniformly coat the wafer. After drying the spin coated layer, the wafer is irradiated with optical energy (hereafter “light”) through a patterned mask. The portion of light passing through the mask reacts with (e.g., oxidizes) the chemical solution layer. Then, wafer is developed such that the oxidized surface portions on the wafer react to form a virtual circuit pattern image. Subsequently, material layers previously formed on the wafer (i.e., under the chemical solution layer) may be selectively removed by various etching processes that use gas and/or other chemical solutions. In this manner, a desired circuit pattern may be formed on the wafer. As one might expect, the provision of the chemical solution onto the wafer is a very important factor in the ultimate quality of the resulting circuit pattern. For example, the thickness of the chemical solution layer covering the wafer is critical to the precision determination of certain critical dimensions (CD) associated with the circuit pattern.
In a conventional application device adapted to coat a wafer with chemical solution (e.g. a photoresist solution), a sensor is routinely installed at a front end of an exchange valve associated with a storage tank to prevent the undesirable generation of air bubbles within the photoresist solution. This sensor is often backed-up by an auxiliary sensor connected between the exchange valve associated with the storage tank and a chemical solution supply tube. In this manner a well controlled flow of photoresist solution may be maintained.
For example, one device adapted to uniformly coat a wafer with photoresist solution is disclosed in U.S. Pat. No. 6,332,924 B1, the subject matter of which is hereby incorporated by reference. This device allows a wafer to be uniformly coated with a chemical solution under uniform discharge pressure provided through a nozzle.
FIG. 1 illustrates an exemplary configuration of a conventional chemical solution dispensing device.
The chemical solution dispensing device includes at least two bottles 12a and 12b containing chemical solution; a chemical supply line 14 forming a flow path for the chemical solution between bottles 12a and 12b; a spin chuck 42 connected to motor 40; and a purge gas supply tube 16 supplying purge gas under pressure to bottles 12a and 12b from a purge gas supply source 11. The chemical solution dispensing device also includes a trap tank 18 extending from each one of bottles 12a and 12b adapted to provide a defined amount of chemical solution to chemical supply line 14, and first and second valves 15 and 17 adapted to control the flow of chemical solution passing through trap tank 18 in response to a control signal received from controller 20. The chemical solution dispensing device also includes a photosensor 24a/24b constructed from a light emitter and a light receiver and adapted to check whether trap tank 18 is filled with chemical solution. A control signal sensed by photosensor 24a/24b received from controller 20 controls the process.
Further, the chemical solution dispensing device includes a pump 19 adapted to provide flow pressure to the chemical solution flowing through chemical supply line 14; a chemical filter 30 adapted to filter foreign matter and air bubbles from the chemical solution flowing though chemical supply line 14; a suck back valve 26 connected behind chemical filter 30 and adapted to provide suction to chemical supply line 14, such that residual drops of sprayed chemical solution do not drop onto a wafer (W) once a spraying operation is completed; and a nozzle 28 connected to suck back valve 26 and adapted to spray the chemical solution. The chemical solution dispensing device also includes a bubble exhaust line 32 and exhaust valve 34 connected to chemical filter 30 and adapted to remove air bubbles from the interior of chemical filter 30.
When a first valve 15 or second valve 17 is opened by controller 20 to coat wafer (W) with chemical solution, the chemical solution flows into pump 19 from bottles 12a and/or 12b. Pump 19 pressurizes the inflowing chemical solution under the control of controller 20, and transfers it to chemical filter 30. Chemical filter 30 filters the pressurized chemical solution. The filtered chemical solution is then sprayed through nozzle 28 under pressure provided by pump 19. Nozzle 28 typically has numerous spraying holes 29 formed at uniform intervals to uniformly spray the chemical solution onto the wafer (W).
When this type of conventional chemical solution dispensing device is used for long durations with photoresist spinner equipment, for example, small blockages may form in some of spraying holes 29 thereby impeding the uniform spraying of chemical solution onto the wafer W. This effect causes defects in quality of the products (e.g., semiconductor devices) ultimately formed on wafer (W).